Automatic compensator component for a motor vehicle drum brake and a motor vehicle drum brake with automatic compensator component

Abstract

The present invention relates to automatic compensation by means of an automatic compensator component for a motor vehicle drum brake, as well as a motor vehicle drum brake comprising the automatic compensator component. A drum brake with a spreading device, exemplified as an electric parking brake actuator (11), has a deformation section (18) arranged in a connecting rod (15). The connecting rod (15) transmits a force from the spreading device / parking brake actuator (11) to a brake shoe (2, 3). The deformation section (18) allows a deformation path (x) of an amount limited to a predetermined wear and tolerance compensation. This results in a particularly simple drum brake design and avoids disruptive noise.

Description

[0001] The invention relates to an automatic compensator suitable and intended for arrangement between the brake shoes of a motor vehicle drum brake, and to a motor vehicle drum brake comprising a brake drum rotatably arranged relative to a support plate, with two brake shoes arranged on the support plate, with a spreading device for pre-tensioning the brake shoes against the brake drum, and with a connecting rod arranged in the force flow between the parking brake actuator and at least one of the brake shoes. Preferably, the drum brake includes an electric spreading device that is provided as a motor-gearbox unit, such as, in particular, an electric parking brake actuator with a de-energized, locked electric parking brake function.

[0002] A drum brake is known, for example, from EP 2 670 997 B1. In this drum brake, a lever actuated by a cable is designed with defined elasticity. The lever is articulated on one side to an actuating cable and on the other side to a brake shoe, with the lever having a predetermined spring characteristic. When the drum brake performs a parking brake function while hot and the brake drum subsequently cools down, the defined elastic compliance prevents jamming or damage to the drum brake.

[0003] A drum brake with a connecting rod is known, for example, from WO 2015 / 101486 A1. In this drum brake, the connecting rod has bearings on a parking brake lever and one of the brake shoes. However, these bearings make the drum brake very complex in its construction.

[0004] The brake shoes of drum brakes are generally held in a retracted, released position by return springs without requiring actuation. An automatically adjustable, wear-dependent telescopic strut / link rod serves to achieve precise spacing. However, temperature fluctuations can still cause play in the transmission elements due to thermal expansion. Drum brake friction components (brake drums, brake shoes) are naturally subject to gradual wear of the friction surfaces, and manufacturing tolerances or installation tolerances of the interacting components can be further sources of play. Wear and installation tolerances can impede the strut / link rod's ability to function without play. Play between the strut / link rod and adjacent components can lead to further wear and / or disruptive rattling noises.

[0005] The invention is based on the problem of further developing an automatic compensator component or the relevant drum brake of the type mentioned above in such a way that it can help to avoid disruptive effects and is also particularly simple in design.

[0006] This problem is solved according to the invention. The invention extends equally to a compensator component, which may be a self-contained, modularly manageable and optionally pre-assembled installation component, as well as to the entirety of a correspondingly completed vehicle drum brake, which is illustrated by way of example in the description with reference to the drawing.

[0007] The solution proposed according to the invention is such that the compensator component according to the invention enables, for the first time, currentless compensation under elastic preload between brake shoes by means of a predefined, special, i.e., integrally arranged, compliance / elasticity. This compliance is, for the first time, very specifically defined, and is arranged, in particular, in equilibrium with the preload or spring stiffness of opposing effective brake shoe return springs.

[0008] The problem is therefore excellently solved by means of a deformation section with a pre-stressed elasticity / flexibility, for example as a defined compensating spring component such that, when the brake / parking brake is released, the deformation section / flexibility is formed for elastic pre-stress of a strut / connecting rod on adjacent components of the drum brake and that a deformation path of the deformation section is limited to a provided wear and tolerance compensation of the components of the drum brake.

[0009] The arrangement with the integral elasticity of the compensator components can be defined such that the connecting rod / strut defined elastically clamped between brake shoes, at least in a released state of a motor vehicle drum brake, is in an elastically prestressed force equilibrium with an opposing elastically prestressed return spring force (6,7).

[0010] In the preferred embodiment of the invention, the deformation section compensates for any potential play with adjacent brake shoes and spreading device or electric parking brake actuator. During service braking as well as with the parking brake engaged, the automatic limitation of the deformation path ensures reliable force transmission via the strut / connecting rod, because after the deformation path is limited, the connecting rod according to the invention can function similarly to a rigid connecting rod / strut. The elasticity, in particular the spring force of the elasticity / compensating spring, is advantageously dimensioned such that it is strong enough to reliably position the ends of the connecting rod in force equilibrium with return springs relative to adjacent areas of the drum brake. Thanks to the invention, the deformation section prevents rattling of the connecting rod when the parking brake actuator is inactive.

[0011] According to another advantageous embodiment of the invention, the connecting rod has a particularly simple design if the connecting rod, together with the deformation section, includes a further section with high rigidity for supporting the brake shoe when the parking brake actuator is engaged. Furthermore, this further section can have a length suitable for use in the drum brake. The further section can be rigid or incorporate a spring accumulator.

[0012] According to another advantageous embodiment of the invention, the necessary deformation path can be easily estimated if the deformation path corresponds to the path of the brake shoe over the wear of a friction lining plus a safety margin. Such a deformation path, plus a safety margin, can amount to 4 to 6 mm for drum brakes in passenger cars.

[0013] According to another advantageous embodiment of the invention, the connecting rod is designed to be particularly simple in construction if the deformation section of the connecting rod has a cylinder and a piston that is longitudinally displaceable therein, and if the piston is supported in the cylinder by the compensating spring. Furthermore, this allows the connecting rod to be manufactured as a pre-assembled component.

[0014] According to another advantageous embodiment of the invention, further simplification of the drum brake's construction is achieved if the piston and cylinder have opposing stops and if, in an unloaded basic position of the connecting rod, the distance between the stops corresponds to the intended deformation path.

[0015] Connecting rods of modern drum brakes are either rigidly manufactured in one embodiment or, in another embodiment, incorporate a spring accumulator. According to another advantageous embodiment of the invention, the drum brake embodiment incorporating the spring accumulator allows for a backlash-free arrangement of the connecting rod if a spring of a spring accumulator is arranged in the further section of the connecting rod and if the compensating spring has a lower spring force than the spring of the spring accumulator. With this design, the spring of the spring accumulator is only loaded when the deformation path of the second section is limited, for example, by the contact of the stops.

[0016] Return springs in drum brakes are generally used to keep the brake shoe away from the brake drum when the actuators are inactive. According to another advantageous embodiment of the invention, interference with the function of the return spring due to the deformation section can be easily avoided if the compensating spring has a lower spring force than a return spring that pulls the brake shoe, supported by the connecting rod, back into its home position.

[0017] According to another advantageous embodiment of the invention, a complex bearing arrangement for the connecting rod on the adjacent component can be easily avoided if the connecting rod and an adjacent component have axially supporting support elements.

[0018] The invention allows for numerous embodiments. To further illustrate its basic principle, two of these are shown in the drawing and described below. This shows in Fig. 1. From a perspective, a section of a drum brake, Fig. 2 schematically a first embodiment of a connecting rod of the drum brake made of Fig. 1 in partial section, Fig. 3 schematically another embodiment of a connecting rod made of Fig. 1.

[0019] Fig. Figure 1 shows a section of a drum brake of a motor vehicle with a support plate 1 and brake shoes 2, 3 with friction linings 4, 5 supported on the support plate 1. For simplification, the brake drum enclosing the brake shoes is only partially shown in the drawing with a dashed line in its contour opposite the brake shoes. In the assembled state, the brake drum is connected to a wheel (not shown) and the support plate 1 to the body of the motor vehicle (also not shown). Two return springs 6, 7 pre-tension the brake shoes 2, 3 against each other and thus away from the brake drum. The drum brake has a brake actuator 8 designed as a wheel brake cylinder as an expanding device for a service brake. An adjusting unit 9 is arranged parallel to the brake actuator 8. The ends of the brake shoes 2, 3 facing away from the brake actuator 8 are supported by a support bearing 10.

[0020] Furthermore, the drum brake has a parking brake actuator 11. The parking brake actuator 11 is connected to a parking brake lever 13 via a parking brake actuator cable 12. The parking brake lever 13 is pivotally mounted about a bearing 14 and is supported by a connecting rod 15 against one of the brake shoes 2.

[0021] Fig. Figure 2 schematically shows the connecting rod 15. Fig. 1 in a partial section. The connecting rod 15 has support elements 16, 17 at its ends that axially support the parking brake lever 13 and one brake shoe 2. The connecting rod 15 has a deformation section 18 and a further section 19 that has a high stiffness relative to the deformation section 18. In this embodiment, the further section 19 is rigid. The deformation section 18 has a piston 21 that is slidable into a cylinder 20 and a compensating spring 22, which supports the piston 21 in the cylinder 20. The connecting rod 15 also has opposing stops 23, 24, which limit the possible deformation by the deformation section 18 to a deformation path X. The compensating spring 22 has a lower spring stiffness than the return springs 6, 7. Fig. 1.

[0022] Fig. Figure 3 shows another embodiment of a connecting rod 115, which extends from the Fig. 2 differs only in that a spring accumulator 125 with a spring 126 pre-tensioned with a defined force is arranged in a further section 119. The function of the spring accumulator 125 comes into play when the parking brake actuator 111 is activated, in the event of possible cooling of the drum brake, or in the event of a reversal of the parking brake torque. If the force in the connecting rod 115 increases beyond the pre-tension force of the spring 126, the length of the connecting rod 115 is reduced.

[0023] A deformation section 118 with a compensating spring 122 is arranged in a row with the further section 119. The compensating spring 122 has a lower stiffness than the spring 126 in the spring accumulator 125, so that here too the compensating spring 122 preloads the ends of the connecting rod 115 against adjacent components of the drum brake. As in the embodiment according to Fig.2 The deformation section 118 has two stops 123, 124 arranged at a distance from each other in an unloaded basic position with a deformation path X, which limit the possible deformation of the deformation section 118. Reference symbol list 1 support plate 2, 3 brake shoe 4, 5 friction lining 6, 7 Return spring 8 Brake actuator 9 Adjustment unit 10 support bearings 11 Parking brake actuator 12 Parking brake actuator cable 13 Parking brake lever 14 Storage 15, 115 connecting rods 16, 17 Support element 18, 118 Deformation section 19, 119 section 20 cylinders 21 pistons 22, 122 compensating spring 23, 24, 123, 124 stop 125 spring storage 126 spring X Deformation path QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 2 670 997 B1

[0002] WO 2015 / 101486 A1

[0003]

Claims

[1] Automatic compensator component for a motor vehicle drum brake, preferably formed as a multi-piece and telescopic connecting rod or strut, characterized by , that the compensator component, namely in particular the connecting rod (15, 115), has a defined elasticity, which is provided in particular by way of example as a compliant deformation section (18, 118), so that an elastically prestressable compliance is defined in such a way that its design-specified deformation path (x) is limited on the basis of a design-specified defined wear dimension range and / or tolerance dimension range in operational cooperation of the components of the motor vehicle drum brake. [2] Automatic compensator component according to claim 1, characterized by, that the constructively specified deformation path (x) of the deformation section (18, 118) is limited to the wear dimension range and / or tolerance dimension range of the drum brake. [3] Automatic compensator components according to one or more of the preceding claims, characterized by , that the elasticity of the compensator component is defined such that an elastically clamped defined connecting rod / strut, at least in a released state of a motor vehicle drum brake, is in a force equilibrium with a permanently imposed return spring force (6,7) when elastically clamped. [4] Automatic compensator component for a motor vehicle drum brake, according to one or more of the preceding claims, characterized by, that the connecting rod (15, 115) with the deformation section (x), preferably aligned in one axis / in series, defines a further section (19, 119) preferably having a fixed stop which is fixed or with a stiffness increased relative to the deformation section (x), namely in particular quasi-rigid, for the purpose of providing firm support of the brake shoe (2, 3) when the brake is applied, as in particular when the parking brake actuator (11) is applied. [5] Automatic compensator component for a motor vehicle drum brake according to one or more of the preceding claims, characterized by , that the deformation path (x) corresponds to the path of the brake shoe (2, 3) over the wear of a friction lining (4, 5) plus a safety margin. [6] Automatic compensator component for a motor vehicle drum brake according to one or more of the preceding claims, characterized by, that the deformation section (18, 118) of the connecting rod (15, 115) has a cylinder (20) and a piston (21) which is longitudinally displaceable therein, and that the piston (21) is supported in the cylinder (20) by the compensating spring (22, 122). [7] Automatic compensator component for a motor vehicle drum brake according to one or more of the preceding claims, characterized by , that the piston (21) and cylinder (20) have opposing stops (23, 24, 123, 124) and that in an unloaded basic position of the connecting rod (15, 115) the distance of the stops (23, 24, 123, 124) corresponds to the intended deformation path (X). [8] Automatic compensator component for a motor vehicle drum brake according to one or more of the preceding claims, characterized by, that in the further section (119) of the connecting rod (115) a spring (126) of a spring accumulator (125) is arranged and that the compensating spring (122) has a lower spring force than the spring (126) of the spring accumulator (125). [9] Automatic compensator component for a motor vehicle drum brake according to one or more of the preceding claims, characterized by , that the compensating spring (22, 122) has a lower spring force than a return spring (6, 7) which pulls the brake shoe (2, 3) supported by the connecting rod (15, 115) back into its home position. [10] Automatic compensator component for a motor vehicle drum brake according to one or more of the preceding claims, characterized by , that the connecting rod (15, 115) and an adjacent component have axially supporting support elements (16, 17). [11] Motor vehicle drum brake with a brake drum rotatably arranged relative to a support plate (1), with two brake shoes (2, 3) arranged on the support plate (1), with a spreading device for displacing and / or clamping the brake shoes (2, 3) against the brake drum, and with a strut / connecting rod (15, 115) arranged in the force flow between the spreading device and at least one of the brake shoes, wherein preferably an electrically actuated brake actuator is provided, which is preferably formed as an electric motor-gearbox unit, such as in particular as an electric parking brake actuator with a de-energized locking electric parking brake function, and comprising an automatic compensator component, in particular according to one or more of the preceding claims 1-10, characterized by, that the connecting rod (15, 115) has a deformation section (18, 118) with an elastically pre-stressed compensating spring (22, 122), that when the parking brake actuator (11) is inactive, the deformation section (18, 118) is designed to pre-stress the ends of the connecting rod (15, 115) against adjacent components of the drum brake, and that a deformation path (x) of the deformation section (18, 118) is limited to a provided wear and tolerance compensation of the components of the drum brake. [12] Motor vehicle drum brake according to claim 11, characterized by , that the connecting rod (15, 115) with the deformation section (x) in a row has a further section (19, 119) with a high stiffness to support the brake shoe (2, 3) when the parking brake actuator (11) is actuated. [13] Motor vehicle drum brake according to one or more of the preceding claims, characterized by, that the deformation path (x) corresponds to the path of the brake shoe (2, 3) over the wear of a friction lining (4, 5) plus a safety margin. [14] Motor vehicle drum brake according to one or more of the preceding claims, characterized by , that the deformation section (18, 118) of the connecting rod (15, 115) has a cylinder (20) and a piston (21) which is longitudinally displaceable therein, and that the piston (21) is supported in the cylinder (20) by the compensating spring (22, 122). [15] Motor vehicle drum brake according to one or more of the preceding claims, characterized by , that piston (21) and cylinder (20) have opposing stops (23, 24, 123, 124) and that in an unloaded basic position of the connecting rod (15, 115) the distance of the stops (23, 24, 123, 124) corresponds to the intended deformation path (X). [16] Motor vehicle drum brake according to one or more of the preceding claims, characterized by, that in the further section (119) of the connecting rod (115) a spring (126) of a spring accumulator (125) is arranged and that the compensating spring (122) has a lower spring force than the spring (126) of the spring accumulator (125). [17] Motor vehicle drum brake according to one or more of the preceding claims, characterized by , that the compensating spring (22, 122) has a lower spring force than a return spring (6, 7) which pulls the brake shoe (2, 3) supported by the connecting rod (15, 115) back into its home position. [18] Motor vehicle drum brake according to one or more of the preceding claims, characterized by , that the connecting rod (15, 115) and an adjacent component have axially supporting support elements (16, 17).

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